WO 2013/007633 discloses a control valve for controlling liquid flow in a heating and/or cooling installation under command from an actuator. The control valve comprises a flow regulator with two annular valve members that have an axial overlap. The one valve member is manually rotatable relative to the second valve member. The axially overlapping portions of the valve members define an inlet opening with a variable circumferential extent. A third valve member is axially displaceable by the actuator relative to the inlet opening and defines a control edge associated with the inlet opening. Rotation of the first valve member relative to the second valve member changes the circumferential extent of the opening, in order to manually preset a maximum through-flow area. Axial displacement of the third valve member changes the axial extent of the through-flow area of the inlet opening, in order to regulate the through-flow area within a range limited by the preset maximum. A differential pressure regulator is provided downstream of the flow regulator, and it regulates the differential pressure across the inlet opening.
The control valve disclosed in WO 2013/007633 has the advantage that it allows for an independent valve member to control the circumferential extent and for another independent valve member to control the axial extent of the effective through-flow area of the flow regulator. Thus the axial movement (the stroke) of the valve remains the same independent of the circumferential extent of the effective through-flow area. The control valve automatically adjusts itself to any flow area if it be adjusted manually or by actuator, axially or circumferential. When the operator presets the valve according to a maximum design flow, the stroke of the control valve remains the same.
However, the control valve disclosed in WO 2013/007633 has the disadvantage that the circumferential extent of the inlet opening is constructionally limited to 180° and axial extent of the effective flow area is limited by the maximum stroke length of the type of actuators that is used for controlling liquid flow in a heating and/or cooling installation.